Physical Pretreatment Research Articles

Opportunities for biogas production from algal biomass

Energy security is a critical global challenge in the transition to sustainable development. Anaerobic digestion (AD) offers a promising renewable energy solution that mitigates environmental impacts. Algae, as biomass feedstock, have shown significant potential for bioenergy production; however, their complex chemical composition poses challenges to the efficiency of the AD process. To address these limitations, various pretreatment methods have been applied to enhance biogas production. In this study, we performed a comprehensive meta‐analysis to evaluate the effects of different pretreatments on methane (CH₄) yields from both microalgae and macroalgae. Our results demonstrate that biological, physical, and combined chemical–physical pretreatments significantly improve CH₄ production in microalgae, with increases of up to 141%, 125%, and 151%, respectively. For macroalgae, physical pretreatments were the most effective, leading to a 129% increase in CH₄ yield. We also estimate that utilizing just 10% of the global algal biomass production (3.6 Mt) could generate over 5.5 TWh y−1 of energy. This potential could be doubled with the application of appropriate pretreatment strategies. These findings highlight the role of algae in advancing renewable energy production and contribute to the growing body of knowledge on optimizing AD processes for cleaner energy generation.

Physical–Chemical–Biological Pretreatment for Biomass Degradation and Industrial Applications: A Review

Lignocellulosic biomass, including agricultural, forestry, and energy crop waste, is one of Earth’s most abundant renewable resources, accounting for approximately 50% of global renewable resources. It contains cellulose, hemicellulose, and lignin, making it crucial for biofuels and bio-based chemicals. Due to its complex structure, single-pretreatment methods are inefficient, leading to the development of combined pretreatment technologies. These methods enhance cellulose accessibility and conversion efficiency. This paper analyzes the principles, advantages, and disadvantages of various combined pretreatment methods and their practical benefits. It highlights recent research achievements and applications in biofuel, biochemical production, and feed. By integrating multiple pretreatment methods, biomass degradation efficiency can be significantly improved, energy consumption reduced, and chemical reagent use minimized. Future advancements in combined physical, chemical, and biological pretreatment technologies will further enhance biomass utilization efficiency, reduce energy consumption, and protect the environment, providing robust support for sustainable renewable energy development and ecological protection.

Effect, Fate and Remediation of Pharmaceuticals and Personal Care Products (PPCPs) during Anaerobic Sludge Treatment: A Review.

Biomass energy recovery from sewage sludge through anaerobic treatment is vital for environmental sustainability and a circular economy. However, large amounts of pharmaceutical and personal care products (PPCPs) remain in sludge, and their interactions with microbes and enzymes would affect resource recovery. This article reviews the effects and mechanisms of PPCPs on anaerobic sludge treatment. Most PPCPs posed adverse impacts on methane production, while certain low-toxicity PPCPs could stimulate volatile fatty acids and biohydrogen accumulation. Changes in the microbial community structure and functional enzyme bioactivities were also summarized with PPCPs exposure. Notably, PPCPs such as carbamazepine could bind with the active sites of the enzyme and induce microbial stress responses. The fate of various PPCPs during anaerobic sludge treatment indicated that PPCPs featuring electron-donating groups (e.g., ·-NH2 and ·-OH), hydrophilicity, and low molecular weight were more susceptible to microbial utilization. Key biodegrading enzymes (e.g., cytochrome P450 and amidase) were crucial for PPCP degradation, although several PPCPs remain refractory to biotransformation. Therefore, remediation technologies including physical pretreatment, chemicals, bioaugmentation, and their combinations for enhancing PPCPs degradation were outlined. Among these strategies, advanced oxidation processes and combined strategies effectively removed complex and refractory PPCPs mainly by generating free radicals, providing recommendations for improving sludge detoxification.

Влияние некоторых видов обработки на продолжительность сушки и органолептические показатели нарезанных баклажанов

Abstract. Eggplant is a common vegetable crop from the Solanaceae family, whose share of global vegetable harvests in 2022 was about 5 %. However, eggplant is thermophylic and its fruits cannot withstand low temperatures due to physiological disorders and quality reduction. This fact and thin covering tissues make the shelf life of eggplant fruits short. For this reason, improving existing methods for preserving the quality and extending the period of use of eggplants is relevant. One of the most popular methods of preserving fresh plant raw materials is drying, but it requires the selection of a method (including pre-treatment of raw materials) and process parameters to preserve the quality of dried products. In the course of the study, the influence of certain types of physical and chemical pre-treatment (microwave frequencies, citric acid, sodium chloride, their combinations) on the drying time and organoleptic characteristics of sliced eggplant fruits of the Chernomor variety was studied. It was found that various types of treatments used influenced the duration of drying of eggplants: treatments with microwave frequencies and citric acid led to a reduction in process time by 31-43 minutes compared to the control; treatments with sodium chloride solution and complex treatments, on the contrary, increased the duration by more than 3 hours. Organoleptic evaluation of dried eggplants showed that the best characteristics were provided by treatment with 1% and 5% citric acid solutions. While pre-treatment with microwave frequencies and NaCl with various parameters gave an unpleasant taste and was accompanied by darkening of the product. The data obtained can be used to improve existing methods of drying eggplants. Key words: eggplants, drying, organoleptic characteristics, super high frequency, citric acid, sodium chloride

Optimized thermal pretreatment for lignocellulosic biomass of pigeon pea stalks to augment quality and quantity of biogas production

By applying heat to the feedstock during the thermal treatment of biomass for the production of biogas, the organic material's biodegradability can be greatly increased. Biogas production is a huge research area for alternate energy production technology. Increased biodegradability, improved methane yield, pathogen, and weed seed destruction, and overall process efficiency are all benefits of this type of pretreatment. It is a useful pretreatment technique for maximizing the production of biogas because it can decrease inhibitory compounds, and increase the digestibility of biomass. This work focused on increasing the efficiency of biogas production from lignocellulosic biomass of pigeon pea stalks by a novel thermal pretreatment. The pigeon pea stalk is initially imposed to physical pretreatment (PT) by an automatic hammer mill which is considered as a base for comparing performance. Thermal pretreatment was carried out for one hour, and two hours durations at different temperatures like 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C. Compared to physically pretreated pigeon pea stalks, 200ᴼC thermal pretreated pigeon pea stalks for two hours have produced 88.41 % higher biogas, 16.14 % increase of cellulose, 19.9 % higher volatile solid removal, and 3.94 % lesser lignin. The enhanced chemical characteristics were ensured by analyzing the chemical composition variations through the FTIR, XRD, and SEM images. So, this is recommended for enhanced biogas production.

Bioethanol production from pineapple fruit waste juice using bakery yeast

The declining oil production stemming from decreasing raw material reserves has clashes with rising demands and has created a supply-demand gap in the overall energy sector. Excessive consumption of fossil fuel oil exacerbates environmental issues, potentially leading to global climate change and increased natural disasters. Consequently, there are efforts in looking for alternate renewable fuel sources. The study included physical pre-treatment, natural hydrolysis, natural fermentation, fermentation of pineapple waste juice using bakery yeast, and subsequent distillation. The pineapple wastes produced juice with 12.67 °Brix and pH range of 3.16–3.18. The present study reports bioethanol production from pineapple waste mixed with bakery yeast (Saccharomyces cerevisiae) and pineapple wastes juice without bakery yeast, revealing that the yeast-amended mixture yielded bioethanol with alcohol content of 45 % compared to 36 % from pineapple juice alone. Re-distillation enhanced bioethanol content from 25 % - 45 %–85 % which aligns well with E85 fuel specifications, indicating bioethanol's suitability as fuel. Thus, bioethanol derived from pineapple fruit wastes presents a promising renewable energy solution. This study investigates the production of bioethanol from pineapple waste juice by comparing two methods: one using bakery yeast and the other without yeast. Both methods are conducted at room temperature to evaluate their efficiency and effectiveness in converting pineapple waste juice into bioethanol.

Thermal chemical pretreatment of waste-activated sludge for enhanced solubilization and biogas production: a review

ABSTRACT Waste-activated sludge (WAS) generation is increasing due to the increased generation of wastewater owing to industrialization and urbanization. The disposal of WAS is a significant environmental and financial concern that can be offset by stabilization and valorization via anaerobic digestion (AD). However, the biodegradation is limited due to microbial cells and extracellular polymeric substances (EPS). Physical, chemical, biological, and hybrid pretreatments and the addition of accelerant materials for enhancing direct interspecies electron transfer (DIET) are among the strategies to overcome the poor biodegradation of WAS. Alkaline pretreatment disintegrates the floc structure of WAS by increasing the osmotic pressure, while microwave irradiation has thermal and a-thermal effects and increases the availability of organics for biodegradation. Moreover, the combination of alkaline and thermal pretreatments has synergic effects on solubilization, biogas production, and dewaterability. The disintegration of WAS is recognized by alteration in volatile solid (VS) content, sCOD, BOD/sCOD, turbidity, nutrients solubilization, dewaterability, particle size, specific surface area, change functional group, alteration in microorganism community, microorganism abundance, color, moisture content, lag phase, and biogas production. Higher doses of pretreatment increase COD solubilization but not biodegradable COD. Maximum COD solubilization ranged from 2 to 37% in alkaline, 21 to 260% in the microwave (MW), and 28 to 624% in hybrid pretreatments.

Pretreatment and fermentation of lignocellulose from oil palm fronds as a potential source of fibre for ruminant feed: a review

AbstractOil palm fronds are plantation waste widely available in large quantities and have great potential as a source of ruminant feed due to their high fibre content. However, the lignocellulose content can inhibit feed digestion. This review examines methods that can reduce the lignocellulose content and improve the nutritional quality of palm fronds. The lignin content of palm fronds ranges from 17% to 20%, while the maximum lignin content in ruminant feed is 7%. Processing processes such as pretreatment are needed to reduce the lignocellulose content. Pretreatment can be done physically, chemically, biologically or in combination with other methods. Physical pretreatment aims to reduce the size of lignocellulose, chemical pretreatment seeks to break the crystallinity structure of lignocellulose with chemical solutions such as acids or alkalis, and biological pretreatment degrades the structure of lignocellulose with the help of enzymes produced by microbes. The protein content of palm fronds also does not meet the feed standard, which is only 5%, while according to Indonesian national standards, ruminant feed, especially cattle, must have a minimum protein content of 14%. Therefore, it is necessary to improve the nutritional quality of palm fronds through fermentation methods. The selection of the right microbes is the main factor in the success of increasing nutrition. The SSF fermentation method is frequently used in feed manufacturing. By synthesizing the current knowledge, this review also highlights the challenges of the pretreatment process as well as solutions that include prospects in the research of palm fronds as ruminant feed, which in turn can contribute to the increased utilization of lignocellulosic waste as animal feed.

Impact of Frailty on Post-Treatment Dysphagia in Patients with Head and Neck Cancer.

In the rising and frail head and neck cancer (HNC) population, geriatric assessments are crucial. Frail HNC patients often experience dysphagia. The coexistence of dysphagia and frailty presents complex health challenges, however, there is limited evidence on the prognostic value of frailty on post-treatment dysphagia. This study explores the relationship between pre-treatment frailty status and post-treatment dysphagia in HNC patients. A retrospective data analysis from the OncoLifeS data-biobank at the University Medical Center Groningen of 242 patients diagnosed with HNC between 2014 and 2016. The study involved several physical, functional and psychological pre-treatment geriatric assessments, and frailty screening using the Groningen Frailty Indicator (GFI) and the Geriatric-8 screening tool (G8). Outcome measures were swallowing-related quality of life (HNSW-QoL) and toxicity-related dysphagia evaluations (CTCAE-D) at 3, 6, 12 and 24 months. Linear mixed-effects models assessed factors associated with HNSW-QoL and CTCAE-D. Frail patients consistently reported worse HNSW-QoL and CTCAE-D than non-frail patients over time, with symptoms increasing at 3 months, but gradually decreasing by 24 months. Frailty status (G8 or GFI) was a significant predictor for lower HNSW-QoL (β = 11.770 and 10.936, both p < 0.001), and lower CTCAE-D (β = 0.245, p = 0.058; β = 0.331, p = 0.019), respectively. In this study, frailty was found to be associated with a worse of swallowing-related quality of life, and with increased toxicity-related dysphagia. These findings provide insights for the identification of HNC patients at higher risk of post-treatment swallowing-related issues, and offer opportunities for optimizing their post-treatment swallowing outcomes.

Bio-physical pre-treatments in anaerobic digestion of organic fraction of municipal solid waste to optimize biogas production and digestate quality for agricultural use

This study optimized the anaerobic digestion (AD) of separated collected organic fractions of municipal solid waste (OFMSW) to produce energy and digestate as biofertilizer. Due to OFMSW’s partial recalcitrance to degradation, enzymatic (UPP2, MCPS, USC4, USE2, A. niger) and physical (mechanical blending, heating, hydrodynamic cavitation) pre-treatments were tested. Experimental and modeling approaches were used to compare AD performance regarding energy sustainability and digestate quality. Digestate was separated into solid and liquid fractions, and then chemically and physically characterized by investigating the nutrient release mechanisms. Principal Component Analysis was applied, equally weighing energy and digestate productions. Unlike previous studies focusing only on biogas, this study evaluated the effects of pre-treatments on both biogas and digestate production, viewing AD as a biorefinery process for urban waste valorization. Results showed that all pre-treatments were energetically sustainable, but enzymatic pre-treatments yielded digestates richer in nutrients (increase of 80% N, 200% P and 150% K as compared to OFMSW) and with greater organic matter degradation compared to physical pre-treatments. The liquid fraction of digestate from enzymatic pre-treatments had higher nutrient concentrations, while those from physical pre-treatments had more balanced nutrient content, making them more suitable for fertigation.

Effect of potassium persulphate-induced microwave pretreatment for cost-effective sludge solubilization and bioenergy recovery

The disintegration of municipal waste activated sludge (MWAS) by energy-intensive physical pretreatments is considered expensive. In the present study, an effort was undertaken to disintegrate the sludge by microwave assisted pretreatment (MAP) in an energy-efficient and economical way by combining the microwave with oxidant potassium persulphate. Besides, the sulphate radicals generated through activated persulfate can efficiently disintegrate and solubilize sludge. In this context, microwave pretreatment was combined with potassium persulfate to activate the generation of sulphate radicals for economically enhanced sludge solubilization. MAP was done by varying the microwave power levels (10 to 50 %) and pretreatment time (0 to 30 min). Microwave assisted potassium persulphate pretreatment (MAPPP) was done by varying the potassium per sulphate dosage (0.005 to 0.04 g/g Total solids (TS) and pretreatment time (0 to 14 min). Combining microwave with potassium persulfate brings about a synergistic effect, generating sulphate and hydroxyl radicals that can effectively disintegrate and solubilize biopolymers of sludge. A higher sludge lysis rate of 37.25 % was achieved by this microwave assisted potassium persulfate pretreatment (MAPPP) when compared to microwave assisted pretreatment (MAP) alone (26.27 % after thickening). A higher methane yield of 219.14 mL/g Volatile solids (VS) was obtained through MAPPP compared to MAP (154.22 mL/g VS). The detailed mass, energy, and economic assessment at a large-scale level for MAP and MAPPP revealed that MAPPP was energetically and economically feasible with an energy ratio of 1.22 and net profit of 42.03 USD/Ton compared to MAP. Thus, it can be confirmed that MAPPP was economically viable to implement on a large scale.

SWCNT fibers decorated with Au nanoparticles as voltammetric sensors for arsenic (III) determination

We developed a new method to produce fiber electrodes from single-walled carbon nanotube (SWCNT) films, which can be employed as a novel sensing platform for electrochemical investigations and analysis. By assembling SWCNT bundles in the form of a strong free-standing fiber with almost entire surface accessible to an analyte, we are able to avoid the interference of substrate and improve detection efficiency. We examined the influence of physical, chemical and electrochemical pretreatments of the new electrode SWCNT material on its properties. Transmission and scanning electron microscopy, Raman spectroscopy and cyclic voltammetry were used to characterize the SWCNT fibers. The modification of the SWCNT fiber electrode with gold nanoparticles provides the necessary analytical characteristics including high repeatability and sensitivity and low detection limit (1.3 – 2.1 μg L-1) for arsenic determination by anodic stripping voltammetry. Arsenic detection parameters such as deposition potential, deposition time and scan rate were optimized. Linear responses were found in concentration ranges from 3 to 210 μg L-1 and 7 to 125 μg L-1 for gold modified SWCNT fiber sensors (the SWCNTs were synthesized using CO or ethanol as precursors) at a relatively low deposition time of 60 s. The developed Au-SWCNT sensors allow rapid As determination in real samples and exhibit high durability and long service life.

Comprehensive insights of pretreatment strategies on the structures and bioactivities variation of lignin-carbohydrate complexes.

Introduction: Due to its unique structural features and bioactivities, the lignin-carbohydrate complex (LCC) displays great potential in vast industrial applications. However, the elucidation of how various pretreatment methods affect the structure and bioactivities remains unaddressed. Method: The three pretreatment methods were systematically studied on the variations of structures and bioactivities, and the Gramineae plant, i.e., wheat straw, was adopted in this study. The structures and bioactivities variation caused by different pretreatments were studied in detail. Result and Discussion: The results showed that compared to physical or chemical pretreatments, biological pretreatment was the most effective approach in improving the bioactivities of LCC. The LCC from biological pretreatment (enzymatic hydrolysis, ELCC4) had more functional groups while the lower weight-average molecular weight (Mw) and polydispersity index (PDI) were well-endowed. The highest antioxidant abilities against ABTS and DPPH of ELCC4 were high up to 95% and 84%, respectively. Furthermore, ELCC4 also showed the best ultraviolet (UV)-blocking rate of 96%, which was increased by 6% and 2% compared to LCC8 (physical pretreatment) and LLCC4 (chemical pretreatment). This work prospectively boosts the understanding of pretreatment strategies on the structures and bioactivities variation of LCC and facilitates its utilization as sustainable and biologically active materials in various fields.

Preparation of waste Camellia oleifera shell and high‐density polyethylene composites: Effect of pretreatment on fiber and materials properties

AbstractThe preparation of wood‐plastic composites (WPCs) with high filling fibers and excellent physical properties remained a great challenge. This study used Camellia oleifera shell (COS, agroforestry product waste) as raw material, and prepared 60 wt% COS/high‐density polyethylene (HDPE) WPCs using profile extrusion method through pretreating fibers including hot water, hot steam, alkali, acid, extraction, and fine fiber screening. After pretreatments, the relative contents of cellulose and lignin increased, the relative contents of hemicellulose and extract decreased significantly, and the length‐diameter ratio was improved. The flexural strength, tensile strength and impact strength of hot water and steam heat treated composites reached 31.4, 17.1 MPa and 6.9 kJ/m2, 31.8, 16.8 MPa and 6.7 kJ/m2, respectively. Compared with untreated 28.8, 14.7 MPa and 5.5 kJ/m2, the advantages were more obvious. Alkali treatment and acid treatment improved the thermal stability and residue rate of the material. Extraction treatment and alkali treatment significantly reduced the processing torque force, which was conducive to processing, while acid treatment was the opposite. The highest water absorption and thickness expansion rate were 13.75% and 3.60% respectively at 7 days after alkali treatment, which were considerably higher than 5.60% and 0.78% without treatment, while other pretreatments improved the dimensional stability of the material.Highlights High filling Camellia oleifera shell waste/HDPE composites were prepared. Physical and chemical pretreatments improved interfacial adhesion of the composites. Heat treatments significantly improved mechanical performance of the composites.

A Comprehensive Review on Starch-Based Hydrogels: From Tradition to Innovation, Opportunities, and Drawbacks.

Natural hydrogels based on renewable and inexpensive sources, such as starch, represent an interesting group of biopolymeric materials with a growing range of applications in the biomedical, cosmeceutical, and food sectors. Starch-based hydrogels have traditionally been produced using different processes based on chemical or physical methods. However, the long processing times, high energy consumption, and safety issues related to the synthesis of these materials, mostly causing severe environmental damage, have been identified as the main limitations for their further exploitation. Therefore, the main scientific challenge for research groups is the development of reliable and sustainable processing methods to reduce the environmental footprint, as well as investigating new low-cost sources of starches and individuating appropriate formulations to produce stable hydrogel-based products. In the last decade, the possibility of physically modifying natural polysaccharides, such as starches, using green or sustainable processing methods has mostly been based on nonthermal technologies including high-pressure processing (HPP). It has been demonstrated that the latter exerts an important role in improving the physicochemical and techno-functional properties of starches. However, as for surveys in the literature, research activities have been devoted to understanding the effects of physical pre-treatments via high-pressure processing (HPP) on starch structural modifications, more so than elucidating its role and capacity for the rapid formation of stable and highly structured starch-based hydrogels with promising functionality and stability, utilizing more sustainable and eco-friendly processing conditions. Therefore, the present review addresses the recent advancements in knowledge on the production of sustainable starch-based hydrogels utilizing HPP as an innovative and clean-label preparation method. Additionally, this manuscript has the ambition to give an updated overview of starch-based hydrogels considering the different types of structures available, and the recent applications are proposed as well to critically analyze the main perspectives and technological challenges for the future exploitation of these novel structures.

Anaerobic treatment of fruit and vegetable wastewater using EGSB: From strategies for regulating over-acidification to microbial community

Fruit and vegetable waste (FVW) are characterized by high-water content. Solid-liquid separation of FVW by crushing-extrusion physical pre-treatment provides fruit and vegetable wastewater (FVWW), and then for anaerobic biological treatment to recover methane, which is considered a cost-effective approach. However, anaerobic treatment of FVWW faces difficulties with low methane productivity and over-accumulation of volatile fatty acids (VFAs). In this study, the expanded granular sludge bed (EGSB) reactor was used for the anaerobic treatment of FVWW and the regulatory strategy to alleviate over-acidification was proposed. When the influent chemical oxygen demand (COD) concentration was 10000 mg/L, the hydraulic retention time (HRT) was 2 days, the organic loading rate (OLR) reached 5 g COD/L/d, the maximum methane productivity reached 301.14 ± 2.32 mL/g COD with a COD removal rate of 96 % ± 2 %. Lower VFAs accumulation was observed when decreasing the influent COD concentration to the same OLR compared with extending HRT, resulting in 38.5 % higher methane productivity. Decreasing the influent COD concentration not only benefited the enrichment of acetogens and hydrogenotrophic methanogens but also specifically enriched syntrophic bacteria. The enhanced syntrophic acetogenesis and hydrogenotrophic methanogens maybe the main reasons for promoting the degradation of propionate and butyrate and improving the methane productivity.

Correction of the Tuberous Breast with Fat Grafting and Implant: Techniques, Evaluation with BREAST-Q, and Preliminary Results.

The correction of tuberous breast deformity with fat grafting has gained popularity in recent years, but it remains unclear whether this new technique can produce patient satisfaction levels comparable to those achieved with implant-based correction. This study aimed to compare patients' satisfaction and quality of life using the BREAST-Q questionnaire after correction of tuberous breast deformity with fat grafting and implants. Twenty-four patients (36 breasts) were included in our study. Thirteen patients (15 breasts) had a correction with lipofilling (mean 2.67 interventions) and 11 patients (21 breasts) had an implant-based correction (mean 1 intervention). Both fat and implant treatments showed statistically significant improvements in breast satisfaction (p value=0.001, 0.002, respectively), psychosocial (p value=0.003, 0.003, respectively), and sexual satisfaction (p value=0.008, 0.002, respectively) between the pre-treatment and post-treatment stages. However, the only statistically significant differences between the treatments were observed in the physical condition pre-treatment (p value=0.008) and sexual condition post-treatment (p value=0.030). The outcome of both treatments was not statistically different. Furthermore, the outcome exhibited a statistically significant positive linear relationship with breast satisfaction for both treatments. This study suggests that lipofilling can achieve breast and outcome satisfaction comparable to that of implants, although this parity in results comes at the cost of more interventions. These preliminary results lend support to the notion that, as surgeons have access to two equally effective techniques, it is crucial to provide appropriate guidance to patients to ensure their satisfaction. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Isolation and characterization of bio-prospecting gut strains Bacillus safensis CGK192 and Bacillus australimaris CGK221 for plastic (HDPE) degradation.

The present work reports the application of novel gut strains Bacillus safensis CGK192 (Accession No. OM658336) and Bacillus australimaris CGK221 (Accession No. OM658338) in the biological degradation of synthetic polymer i.e., high-density polyethylene (HDPE). The biodegradation assay based on polymer weight loss was conducted under laboratory conditions for a period of 90days along with regular evaluation of bacterial biomass in terms of total protein content and viable cells (CFU/cm2). Notably, both strains achieved significant weight reduction for HDPE films without any physical or chemical pretreatment in comparison to control. Hydrophobicity and biosurfactant characterization were also done in order to assess strains ability to form bacterial biofilm over the polymer surface. The post-degradation characterization of HDPE was also performed to confirm degradation using analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electronic microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX), and Gas chromatography-mass spectrometry (GC-MS). Interestingly strain CGK221 was found to be more efficient in forming biofilm over polymer surface as indicated by lower half-life (i.e., 0.00032day-1) and higher carbonyl index in comparison to strain CGK192. The findings reflect the ability of our strains to develop biofilm and introduce an oxygenic functional group into the polymer surface, thereby making it more susceptible to degradation.

Transparent Cellulose/Multi-Walled Carbon Nanotube Hybrids with Improved Ultraviolet-Shielding Properties Prepared from Cotton Textile Waste.

Plastics offer many advantages and are widely used in various fields. Nevertheless, most plastics derived from petroleum are slow to degrade due to their stable polymer structure, posing serious threats to organisms and ecosystems. Thus, developing environmentally friendly and biodegradable plastics is imperative. In this study, biodegradable cellulose/multi-walled carbon nanotube (MCNT) hybrid gels and films with improved ultraviolet-shielding properties were successfully prepared using cotton textile waste as a resource. It was proven that MCNTs can be dispersed evenly in cellulose without any chemical or physical pretreatment. It was found that the contents of MCNTs had obvious effects on the structures and properties of hybrid films. Particularly, the averaged transmittance of cellulose/MCNT composite films in the range of 320-400 nm (T320-400) and 290-320 nm (T290-320) can be as low as 19.91% and 16.09%, when the content of MCNTs was 4.0%, much lower than those of pure cellulose films (T320-400: 84.12% and T290-320: 80.03%). Meanwhile, the water contact angles of the cellulose/MCNT films were increased by increasing the content of MCNTs. Most importantly, the mechanical performance of cellulose/MCNT films could be controlled by the additives of glycerol and MCNTs. The tensile strength of the cellulose/MCNT films was able to reach as high as 20.58 MPa, while the elongation at break was about 31.35%. To summarize, transparent cellulose/MCNT composites with enhanced ultraviolet-shielding properties can be manufactured successfully from low-cost cotton textile waste, which is beneficial not only in terms of environmental protection, but also the utilization of natural resources.

Agricultural Wastes and Their By-Products for the Energy Market

The conversion of lignocellulosic agricultural waste into biofuels and other economically valuable compounds can reduce dependence on fossil fuels, reduce harmful gas emissions, support the sustainability of natural resources, including water, and minimize the amount of waste in landfills, thus reducing environmental degradation. In this paper, the conversion of agricultural wastes into biomethane, biohydrogen, biodiesel, bioethanol, biobutanol, and bio-oil is reviewed, with special emphasis on primary and secondary agricultural residues as substrates. Some novel approaches are mentioned that offer opportunities to increase the efficiency of waste valorization, e.g., hybrid systems. In addition to physical, chemical, and biological pretreatment of waste, some combined methods to mitigate the negative effects of various recalcitrant compounds on waste processing (alkali-assisted thermal pretreatment, thermal hydrolysis pretreatment, and alkali pretreatment combined with bioaugmentation) are evaluated. In addition, the production of volatile fatty acids, polyhydroxyalkanoates, biochar, hydrochar, cellulosic nanomaterials, and selected platform chemicals from lignocellulosic waste is described. Finally, the potential uses of biofuels and other recovered products are discussed.